//https://leetcode.cn/problems/max-area-of-island/

class Solution {
    int dx[4] = { 0,0,-1,1 };
    int dy[4] = { -1,1,0,0 };
    int m, n;
    bool vit[51][51];
public:
    int maxAreaOfIsland(vector<vector<int>>& grid) {
        m = grid.size(), n = grid[0].size();
        int ret = 0;

        for (int i = 0; i < m; i++)
        {
            for (int j = 0; j < n; j++)
            {
                if (grid[i][j] == 1 && !vit[i][j])
                {
                    ret = max(ret, bfs(grid, i, j));
                }
            }
        }

        return ret;


    }

    int bfs(vector<vector<int>>& grid, int i, int j)
    {
        queue<pair<int, int>> q;
        q.push({ i,j });
        vit[i][j] = true;
        int count = 0;
        count++;

        while (q.size())
        {
            auto [a, b] = q.front();
            q.pop();

            for (int k = 0; k < 4; k++)
            {
                int x = a + dx[k];
                int y = b + dy[k];

                if (x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == 1 && !vit[x][y])
                {
                    count++;
                    q.push({ x,y });
                    vit[x][y] = true;
                }
            }
        }

        return count;
    }
};